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I finally have the computer disassembled all the way. Here are my findings on the power supply and the board set:

OK, you do indeed have a "MX" floppy controller and a color graphics board (firmware revision 181 -- earler, and buggy one). What type of floppy drives did you get?

Originally Posted by Terry Kennedy

That seems to be a pretty weird memory layout on the board with the CPU (КМ1801ВМ3) - there are 4 rows of 11 64K chips (КР565РУ5). One of the other boards (with 3 blue headers) has a more normal arrangement of 2 rows of 9 КР565РУ5. Unfortunately, I can't make out the part numbers on some of the other white ceramic parts (low resolution / contrast).

I have friends here, who work with these DVK retrocomputers - so called "REtrocomputer_Club of people who like Soviet/Eastern Block machines "

Heh, that is quite the group name... No one will ever misconstrue what they are about! It's good to see that there is a healthy interest in retro computers in Russia. Maybe you or one of these fellows could help me fix my hard disk controller. Mihail claims I will have to remove it, or else memory check failures will cause the system to not boot. I would appreciate it!

I think that one came up in my search on Amazon recently, but it wasn't clear to me if it could convert 120/60 to 220/50. Someone is looking at the documentation for me, particularly section 3.5.6 of the power supply manual where evidently it states "The unit provides for the possibility of external synchronization of the master oscillator of voltage converters with a horizontal scan rate of 15.4 kHz".

Also, 22 seems to be a "reserved word" around these parts. I didn't realize the 74LS630 was a thing -- hadn't really ventured that high in the 74-series logic family -- but my assumption was the odd arrangement of RAM chips would have been to support the 22-bit physical addresses that can be used by the КМ1801ВМ3: http://www.155la3.ru/datafiles/km1801vm3.pdf However, I think that devoting all 22 chips for an address would defeat the purpose of installing these EDAC chips, not to mention risky from an electrical error perspective. And thanks for all the rest of that good information.

Oh, I forgot to mention, for those of you who want to play along at home with the Russian PDP-11 and KM1801BM3 goodness: there's an emulator for Windows (for lots of DVK systems, not just the 3) that Mihail provided me at https://www.dropbox.com/s/oiecbqlich...0%9A-3.7z?dl=0 . I don't know what the original source is, but it contains docs and a PDP-11 emulator with the configs for this processor. Since my Windows version didn't take too kindly to Cyrillic characters, I had to rename ДВК-3.cfg to DVK-3.cfg and update the reference to that file in the pdp11.ini file so that it would stop complaining to me about a missing config file.

Once you get it running (and you might need to toggle Num Lock if you're like me and using a laptop with shared alphabet/numpad), it's pretty easy to load up Tetris. The fun part is finding the mapping of Cyrillic to Latin characters on the keyboard, since unfortunately the Cyrillic phonetic sounds don't map to the Latin characters as we see them on ours. Nevertheless, this picture of a keyboard will help: https://drive.google.com/file/d/0ByR...ZrYVhMQ2s/view

Last edited by mrcity; September 13th, 2017 at 10:05 PM.
Reason: More info on the emulator

Oh, I forgot to mention, for those of you who want to play along at home with the Russian PDP-11 and KM1801BM3 goodness: there's an emulator for Windows (for lots of DVK systems, not just the 3) that Mihail provided me at https://www.dropbox.com/s/oiecbqlich...0%9A-3.7z?dl=0 . I don't know what the original source is, but it contains docs and a PDP-11 emulator with the configs for this processor. Since my Windows version didn't take too kindly to Cyrillic characters, I had to rename ДВК-3.cfg to DVK-3.cfg and update the reference to that file in the pdp11.ini file so that it would stop complaining to me about a missing config file.

Once you get it running (and you might need to toggle Num Lock if you're like me and using a laptop with shared alphabet/numpad), it's pretty easy to load up Tetris. The fun part is finding the mapping of Cyrillic to Latin characters on the keyboard, since unfortunately the Cyrillic phonetic sounds don't map to the Latin characters as we see them on ours. Nevertheless, this picture of a keyboard will help: https://drive.google.com/file/d/0ByR...ZrYVhMQ2s/view

I think that one came up in my search on Amazon recently, but it wasn't clear to me if it could convert 120/60 to 220/50. Someone is looking at the documentation for me, particularly section 3.5.6 of the power supply manual where evidently it states "The unit provides for the possibility of external synchronization of the master oscillator of voltage converters with a horizontal scan rate of 15.4 kHz".

This doesn't sound like it has anything to do with the AC line frequency though. I'd be really surprised if anything like this, i.e. a non-consumer high-end computer, has any issues at all with being powered at anything between 50 to 60 Hz. And as I mentioned in an earlier post, even 400 Hz power should be perfectly fine too.

I think that one came up in my search on Amazon recently, but it wasn't clear to me if it could convert 120/60 to 220/50. Someone is looking at the documentation for me, particularly section 3.5.6 of the power supply manual where evidently it states "The unit provides for the possibility of external synchronization of the master oscillator of voltage converters with a horizontal scan rate of 15.4 kHz".

CM5508 hard disk is a Bulgarian near-clone of ST-412 (see http://oldpc.su/articles/hdd/hdd.html). That article warns that heads may stick to the platters and recommends 'shaking' the drive before powering it on.

The Elektronika 7-06K clock manual says the same thing, except 220 +/- 22V. This is probably some standard boilerplate, just like old (tube) radio manuals in the US said 117V, even though that was never really a standard.

Even more amusing, the 7-06K has jumpers on the transformer to reconfigure it for 110V:

I took just the power supply over to the local makerspace, which has an APT VariPlus 105 AC power converter, and I verified the voltages on the PSU! No "АВАРИЯ" ("accident") light, yay! My +5V reads +5.3, +12V is +12.3, and -12V is -12.1. I'm sure that when I add the components back in and restore the load on the PSU, it'll drop that +5V to back within tolerance. I also went through all the pins (not just the test points) and was impressed that only two of the DC output pins had 0.02V of ripple; the rest showed no AC ripple at all on the true RMS multimeter.

Originally Posted by shattered

Yours truly is working (on and off) on MAME driver for DVK series. (Your setup should be able to run that ) -- and other good points

Wow, that'll be cool! I can't wait to take it for a spin. I guess that explains why you know so much about the hardware.

I didn't see any obvious issues with the capacitors (i.e. bulges or leaked electrolytic goo), so I left them alone. I'll have to fix the clackety fan before I even have a chance at hearing if there's whistling. I've never even come across DS-QD disk equipment (even after picking over a guy's warehouse with NIB 8" floppies and drives), so I really hope Mihail can get the media he has past customs and to me. As for un-sticking old MFM drives, it's something I'll need to practice. I certainly have some lined up in the queue. Maybe that's a class idea for the local makerspace.

Originally Posted by cthulhu

I'd be really surprised if anything like this, i.e. a non-consumer high-end computer, has any issues at all with being powered at anything between 50 to 60 Hz.

Yeah, I think the power supply itself could handle it (in fact, it could even run cooler). There are still 3 signals I'm not sure of where they are coming from, but that get transferred through PSU pins: Ии∂.осм (си) (elsewhere written as Ии∂.ост (си)), КПРТ, and Осм. These are abbreviations but my translator didn't know what they stand for and my quick Google searches didn't turn up anything. Nevertheless, they show up on pages 2 and 3 of http://forum.maxiol.com/index.php?ac...e=post&id=8291. It's doubtful they relate to the PSU, since on page 3 they are probably shown as inputs that just lead straight back out, but it'd be nice to know for sure. I suppose I could take it back to the makerspace and try the 60Hz mode on the power converter once it's back together to make sure it'd work OK after getting a feel for how it works at 50.

Originally Posted by Terry Kennedy

Even more amusing, the 7-06K has jumpers on the transformer to reconfigure it for 110V.

Heh, if only... I'll have to go over it carefully to see if it has that. However, I doubt it; the Soviets made certain things for export and I doubt this was one of them.

There are still 3 signals I'm not sure of where they are coming from, but that get transferred through PSU pins: Ии∂.осм (си) (elsewhere written as Ии∂.ост (си)), КПРТ, and Осм. These are abbreviations but my translator didn't know what they stand for and my quick Google searches didn't turn up anything. Nevertheless, they show up on pages 2 and 3 of http://forum.maxiol.com/index.php?ac...e=post&id=8291. It's doubtful they relate to the PSU, since on page 3 they are probably shown as inputs that just lead straight back out, but it'd be nice to know for sure.

Two of these three originate on the front panel:
- "Ост" is sent by "ПУЛЬТ" button and goes to the HALT line on the bus. This causes CPU to go into "HALT" mode and run ODT.
- "КПРТ" enables line clock interrupt via BEVNT bus signal.

"Инд. ост (СИ)" -- external sync source for the PWM mentioned in the manual ("The unit provides for the possibility of external synchronization of the master oscillator of voltage converters with a horizontal scan rate of 15.4 kHz".), likely unused.